API combine two sliders - performance issues

Hello,
I would like to combine two sliders. When I klick next in one slider the other slider should go to the next content too.
var slider1 = $("#royalSlider").data('royalSlider');
var slider2 = $("#contentslider2").data('royalSlider');
slider1.ev.on('rsAfterSlideChange',function() {
slider2.goTo( slider1.currSlideId);
});
this works fine - but it is slow. The second lider waits until the first slider is done. (That is what "AfterSlideChange" means). Do you have an idea how to combine the two sliders so that a click on next moves both sliders immediately to the next content?
Thank You
Dirk